P0171 99Lexus Rx300 - Toyota Tundra Forums : Tundra Solutions Forum

cipiripi · #1 (**permalink**) 11-19-2007, 09:35 PM

Have the check engine light on 99 Lexus RX 300. The scan tool showing code P0171. Please let me know what is causing this code and how to test it. The car has 68000 miles and it is 2WD.
Thanks

mral1515 · #2 (**permalink**) 11-20-2007, 10:28 AM

You should probally either clean or replace your mass air flow sensor. It is located on air intake box where your air filter is. Usually there is a small wire inside that get dirt or grime on it. When this happens it can not read how much air is comming through. You can remove the 2 small screws and clean the wires inside it with brake parts cleaner. This will work only some time you, still may have to replace it. You will need to reset the check engine light and test drive when you are done.

integraGSR · #3 (**permalink**) 11-22-2007, 01:22 AM

have you ran out of gas lately? if so, p0171 will set also. p0171 is "system too lean". if you have not ran out of gas lately, with that code, most of the time you will have bad performance. your vehicle will not have the "up and go" as it used to. a quick lesson. the MAF gets dirty and does not read correctly so it sends info to the ECM to send less fuel, which causes the ECM to throw a code of "system too lean". hopefully makes sense.

cipiripi · #4 (**permalink**) 11-25-2007, 06:14 PM

Quote:

Originally Posted by integraGSR

have you ran out of gas lately? if so, p0171 will set also. p0171 is "system too lean". if you have not ran out of gas lately, with that code, most of the time you will have bad performance. your vehicle will not have the "up and go" as it used to. a quick lesson. the MAF gets dirty and does not read correctly so it sends info to the ECM to send less fuel, which causes the ECM to throw a code of "system too lean". hopefully makes sense.

Thank you all for your help. Cleaning the MAF sensor did not help, but new sensor took care of problem.